Addressing sex-based disparities in solid organ transplantation in the United States - a conference report

Trends in Kidney Allograft Failure Among First-Time Transplant Recipients in the United States

RATIONALE & OBJECTIVE

The management and outcomes of kidney transplant recipients have evolved over the past 3 decades. This study of US patients whose first kidney allograft failed examined long-term trends in subsequent waitlisting, retransplantation, and all-cause mortality.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

Patients recorded in the US Renal Data System (USRDS) whose first kidney allograft failed between 1990 and 2019.

EXPOSURE

The 5-year period in which the allograft failure occurred: 1990-1994, 1995-1999, 2000-2004, 2005-2009, 2010-2014, or 2015-2019.

OUTCOME

(1) Waitlisting for retransplantation, (2) retransplantation, and (3) all-cause mortality following first allograft failure.

ANALYTICAL APPROACH

Competing risk survival analyses with the approach described by Fine and Gray used for the outcomes of waitlisting and retransplantation, and Cox proportional hazards models used for the outcome of all-cause mortality.

RESULTS

The absolute number of patients whose allograft failed and who started dialysis increased from 3,197 in 1990 to 5,821 in 2019. Compared with 1990-1994, the rate of waitlisting for a second transplant increased with each subsequent 5-year period, peaking between 2005 and 2009 before decreasing again subsequently. The rate of retransplantation following allograft failure decreased by 9%, 14%, 18%, 7%, and 11% in the sequential 5-year eras; and the mortality rate was 25% lower in 2015-2019 (HR, 0.75 [95% CI, 0.72-0.77]) compared with 1990-1994. Women had a reduced rate of waitlisting (HR, 0.93 [95% CI, 0.91-0.95]) and lower rate of retransplantation (HR, 0.93 [95% CI, 0.91-0.95]) compared with men. Compared with White patients, African American and Hispanic patients had significantly lower rates of waitlisting, retransplantation, and mortality.

LIMITATIONS

Retrospective data that lacks granular clinical information.

CONCLUSIONS

During the past 3 decades, among patients whose first kidney allograft failed and subsequently initiated dialysis, the rates of waitlisting for retransplantation increased while the rates of retransplantation and mortality decreased. Disparities based on race, ethnicity, and sex in waitlisting and retransplantation were observed and warrant further investigation.

PLAIN-LANGUAGE SUMMARY

Kidney allograft failure constitutes the fourth most common cause of dialysis initiation in the United States, and it accounts for 4% to 10% of yearly new dialysis starts globally. Little is known about the trends in the outcomes of patients whose kidney allograft failed. We studied US patients whose first kidney allograft failed between 1990 and 2019 to understand trends in waitlisting for retransplantation, retransplantation, and all-cause mortality after kidney allograft failure. Among patients whose first kidney allograft failed and started dialysis, rates of waitlisting increased and rates of retransplantation and mortality decreased over the past 3 decades. We found racial, ethnic, and sex-based disparities in outcomes. Compared with White patients, African American and Hispanic patients had significantly lower rates of waitlisting, retransplantation, and mortality. Women also had lower rates of waitlisting and retransplantation compared with men.

Retransplantation in Living Donor Liver Transplantation

The need for retransplantation after living donor liver transplantation can occur early, mainly because of technical difficulties such as hepatic artery thrombosis or as a result of early allograft dysfunction as a symptom of small-for-size syndrome. Patients with autoimmune diseases may develop progressive graft failure from recurrent disease. The ethics of retransplantation can be complicated by the cause of the initial liver disease, which may be self-inflicted or the outcome of malignancy. This is especially true in countries without the availability of deceased donors for salvage, and a second living donor would be needed. Nevertheless, patients who experience early or late graft failure should be considered for retransplant if they are deemed acceptable candidates. When a living donor is required for retransplant, the equipoise between donor risk and autonomy and recipient outcome should be considered.

Sex and Gender-related Disparities in Clinical Characteristics and Outcomes in Heart Transplantation

PURPOSE OF REVIEW

Limited research has been conducted on sex disparities in heart transplant (HT). The aim of this review is to analyse the available evidence on the influence of sex and gender-related determinants in the entire HT process, as well as to identify areas for further investigation.

RECENT FINDINGS

Although women make up half of the population affected by heart failure and related mortality, they account for less than a third of HT recipients. Reasons for this inequality include differences in disease course, psychosocial factors, concerns about allosensitisation, and selection or referral bias in female patients. Women are more often listed for HT due to non-ischaemic cardiomyopathy and have a lower burden of cardiovascular risk factors. Although long-term prognosis appears to be similar for both sexes, there are significant disparities in post-HT morbidity and causes of mortality (noting a higher incidence of rejection in women and of malignancy and cardiac allograft vasculopathy in men). Additional research is required to gain a better understanding of the reasons behind gender disparities in eligibility and outcomes following HT. This would enable the fair allocation of resources and enhance patient care.

Experience of Chronic Kidney Disease and Perceptions of Transplantation by Sex

Importance

The pathway to kidney transplantation (KT) begins with the patient's acceptance of this surgical procedure after discussion with the nephrologist. The patients' perceptions of the disease and of KT may influence their willingness to undergo transplantation.

Objective

To describe patients' experiences of kidney disease and their perceptions of KT and the nephrologists' perceptions of the patient experience.

Design, Setting, and Participants

This qualitative study collected data through semistructured interviews with patients with chronic kidney disease and nephrologists in the Bretagne, Île-de-France and Normandie regions, France. Researchers involved in the study in each region purposely selected 99 patients with chronic kidney disease who initiated dialysis in 2021, based on their age, sex, dialysis facility ownership, and also 45 nephrologists, based on their sex and years of experience. Data analysis was performed from January to October 2023.

Main Outcomes and Measures

Themes were identified using inductive thematic analysis. Specific characteristics of men and women as well as the nephrologist's views for each theme were described.

Results

This study included 42 men and 57 women (56 [57%] aged 60 years or older) who started dialysis in 2021 and 45 nephrologists (23 women and 22 men). Six major themes were identified: (1) burden of chronic kidney disease on patients and their families, (2) health care professional-patient relationship and other factors that modulate chronic kidney disease acceptance, (3) dialysis perceived as a restrictive treatment, (4) patients' representation of the kidney graft, (5) role of past experiences in KT perception, and (6) dualistic perception of KT. In some cases, women and nephrologists indicated that women's perceptions and experiences were different than men's; for example, the disease's psychological impact and the living donor KT refusal were mainly reported by 8 women.

Conclusions and Relevance

Patients' past experience of chronic kidney disease in general and of KT in particular, as well as their relationship with their family and nephrologist, were substantial determinants of KT perception in this qualitative study. Targeted policies on these different factors might help to improve access to KT, and more research is needed to understand whether there are sex-based disparities.

Impact of sex on the outcomes of deceased donor liver transplantation

BACKGROUND

Data examining the impact of sex on liver transplant (LT) outcomes are limited. It is clear that further research into sex-related differences in transplant patients is necessary to identify areas for improvement. Elucidation of these differences may help to identify specific areas of focus to improve on the organ matching process, as well as the peri- and post-operative care of these patients.

AIM

To utilize data from a high-volume Eurotransplant center to compare characteristics of male and female patients undergoing liver transplant and assess asso ciation between sex-specific variables with short- and long-term post-transplant outcomes.

METHODS

A retrospective review of the University of Essen's transplant database was performed with collection of baseline patient characteristics, transplant-related data, and short-term outcomes. Comparisons of these data were made with Shapiro-Wilk, Mann-Whitney U, χ2 and Bonferroni tests applied where app ropriate. A P value of < 0.05 was accepted as statistically significant.

RESULTS

Of the total 779 LT recipients, 261 (33.5%) were female. Female patients suffered higher incidences of acute liver failure and lower incidences of alcohol-related or viremic liver disease (P = 0.001). Female patients were more likely to have received an organ from a female donor with a higher donor risk index score, and as a high urgency offer (all P < 0.05). Baseline characteristics of male and female recipients were also significantly different. In multivariate hazard regression analysis, recipient lab-Model for End-Stage Liver Disease score and donor cause of death were associated with long-term outcomes in females. Pre-operative diagnosis of hepatocellular carcinoma, age at time of listing, duration of surgery, and units transfused during surgery, were associated with long-term outcomes in males. Severity of complications was associated with long-term outcomes in both groups. Overall survival was similar in both males and females; however, when stratified by age, females < 50 years of age had the best survival.

CONCLUSION

Female and male LT recipients have different baseline and transplant-related characteristics, with sex-specific variables which are associated with long-term outcomes. Female recipients < 50 years of age demonstrated the best long-term outcomes. Pre- and post-transplant practices should be individualized based on sex-specific variables to optimize long-term outcomes.

The combinatorial effect of age and biological sex on alloimmunity and transplantation outcome

Both age and biological sex affect transplantation outcomes. We have recently shown in a large volume clinical analysis utilizing the SRTR data that graft survival is inferior in young female kidney transplant recipients. In this multi-factorial analysis, older female recipients presented with a trend towards improved transplant outcomes compared to both young female recipients and male recipients of any age. Those data supported by reports of those of others suggest that sex and age impact alloimmune responses both, individually and synergistically. Biological sex and hormone levels change throughout a lifetime with recognized effects on longevity in addition to an impact on the development and course of several disease preconditions. Detailed mechanisms of those sex and age-specific aspects have thus far been studied outside of transplantation. Effects on alloimmunity are largely unknown. Moreover, the combinatorial impact that both, biological sex and age have on transplant outcomes is not understood. Here, we summarize available data that analyze how age in combination with biological sex may shape alloimmune responses and affect transplant outcomes.

Act Together and Act Now to Overcome Gender Disparity in Organ Transplantation

Gender disparity refers to the unequal treatment or a perception of individuals based on their gender and arises from differences in socially constructed gender roles. In the field of transplantation, gender inequality arises at different stages, affecting access to medical care, donation practices, and posttransplant followup care. Gender disparity in transplantation is not limited to any geographic region but is thought to be more prevalent in developing nations. An unusually high number of female donations with relatively fewer female recipients is not only attributable to the low economy but a congregation of medical, social, cultural, and psychological factors. Gender disparities can also be shown in transplant-related professional societies. This review highlights the complexities of spousal donation and vulnerability of women, especially in the developing world. There is a growing need to further modify transplant policies to tackle gender disparities, especially in living related donation. Systematic research in the context of gender-related concerns in transplantation will further aid in understanding the complexities and formulating policies for eliminating gender disparities. Gender disparity is a global problem and not merely limited to transplantation.

Sex Differences in Cardiac Transplantation

PURPOSE OF REVIEW

The goal of this review was to summarize contemporary evidence surrounding sex differences in heart transplantation (HT).

RECENT FINDINGS

Women have steadily comprised approximately 25% of waitlist candidates and HT recipients. This disparity is likely multifactorial with possible explanations including barriers in referral to advanced heart failure providers, implicit bias, and concerns surrounding sensitization. Women continue to experience higher waitlist mortality at the highest priority tiers. After HT, there are differences in post-transplant complications and outcomes. Future areas of study should include sex differences in noninvasive surveillance, renal outcomes after transplantation, and patient-reported outcomes. There are important sex-specific considerations that impact candidate selection, donor matching, waitlist and post-transplant outcomes. Concerted efforts are needed to improve referral patterns to ensure transplantation is allocated equally.

Identifying inequities in lung transplantation: a call for strategies and future research

Innovations in organ preservation, surgical technique, and postoperative care have transformed solid organ transplantation. As organ transplantation becomes more common, potential racial, ethnic, and socioeconomic inequities in the referral and selection process are also emerging. Research studies highlight that patients from minoritized and low socioeconomic groups experience lower rates of referrals, reduced access to the transplant waitlist, higher rates of postoperative complications, and higher mortality rates for cardiothoracic (lung/heart) and abdominal (liver/kidney/pancreas) transplants. Yet, the drivers of these inequities are understudied and thus poorly understood. Strategies that address the root causes and mitigate these inequities are urgently needed. The purpose of this manuscript is not to be a systematic review, partially because there is limited research in this area, but to lay a roadmap toward equity in lung transplant. We highlight the available literature on lung transplantation inequities, identify critical needs, and propose strategies for the next steps. Our goal is to urge a call to action for the research community to systematically address the research in lung transplant disparities, and for health systems, organizations, and policymakers to implement the organizational and health system changes to meaningfully reduce these disparities.

Patient and Provider Gender and Kidney Transplant Referral in Canada: A Survey of Canadian Healthcare Providers

BACKGROUND

Referral for kidney transplant (KT) is variable, with women often disadvantaged. This study aimed to better characterize Canadian transplant referral practices and identify potential differences by respondent and/or patient gender using surveys targeted at healthcare practitioners (HCPs) involved in KT.

METHODS

Surveys consisting of 25 complex patient cases representing 7 themes were distributed to KT HCPs across Canada (March 3, 2022-April 27, 2022) using national nephrology/transplant society email registries. Respondents were asked whether they would refer the patient for transplant. Two identical surveys were created, differing only by gender/gender pronouns used in each case. Multivariable logistic regression was used to assess the association of respondent demographics and patient themes (including case gender) with the odds of transplant referral (overall and stratifying by respondent gender).

RESULTS

Overall, the referral rate was 58.0% among 97 survey respondents (46.4% male). Case themes associated with a lower likelihood of referral included adherence concerns (adjusted odds ratio [aOR] 0.65; 95% confidence interval [CI], 0.45-0.94), medical complexity (aOR 0.57; 95% CI, 0.38-0.85), and perceived frailty (aOR 0.63; 95% CI, 0.47-0.84). Respondent gender was not associated with differences in KT referral (aOR 0.91; 95% CI, 0.65-1.26 for male versus female respondents) but modified the association of frailty (less referral for male than female respondents, P  = 0.005) and medical complexity (less referral for female than male respondents, P  = 0.009) with referral. There were no differences in referral rate by case gender ( P  = 0.82).

CONCLUSIONS

KT referral practices vary among Canadian HCPs. In this study, there were no differences in likelihood of transplant referral by candidate gender.

Sex differences in chronic liver disease and benign liver lesions

The epidemiology, natural history, and therapeutic responses of chronic liver diseases and liver lesions often vary by sex. In this review, we summarize available clinical and translational data on these aspects of the most common liver conditions encountered in clinical practice, including the potential contributions of sex hormones to the underlying pathophysiology of observed differences. We also highlight areas of notable knowledge gaps and discuss sex disparities in access to liver transplant and potential strategies to address these barriers. Given established sex differences in immune response, drug metabolism, and response to liver-related therapies, emerging clinical trials and epidemiological studies should prioritize dedicated analyses by sex to inform sex-specific approaches to liver-related care.

Understanding and Investigating Sex-Based Differences in Heart Transplantation: A Call to Action

Women represent only about 25% of heart transplant recipients annually. Although the number of women living with advanced heart failure remains unknown, epidemiologic research suggests that more women should be receiving advanced heart failure therapies. Sex differences in risk factors, presentation, response to pharmacotherapy, and outcomes in heart failure have been well described. Yet, less is known about sex differences in heart transplant candidate selection, waitlist management, donor selection, perioperative considerations, and post-transplant management and outcomes. The purpose of this review was to summarize the existing published reports related to sex differences in heart transplantation, highlighting areas in which sex-based considerations are well described and supported by available evidence, and emphasizing topics that require further study.

The sex disparity in liver transplantation

PURPOSE OF THE REVIEW

This review describes the sex disparity in liver transplantation (LT) and explains its underlying causes.

RECENT FINDINGS

There is a small but persistent sex disparity in transplant rate and waitlist mortality that disappears once women are listed as Status 1. Allocation systems that could replace the Model for End Stage Liver Disease (MELD)-Na with scores less reliant on serum creatine and muscle mass have the potential to alleviate part of the sex disparity. Women perform worse on frailty assessments and are more likely to have nonalcoholic steatohepatitis (NASH). A diagnosis of NASH is compounding risk factor for frailty.

SUMMARY

Women remain disadvantaged in their access to LT despite multiple evolutions of the allocation system. An allocation system that relies less heavily on serum creatinine could partially alleviate the sex disparity. As NASH becomes more prevalent and frailty becomes more important in listing decisions, we may also need to carefully consider differences in the manifestations of frailty between the genders.

Delayed referral for liver transplant evaluation worsens outcomes in chronic liver disease patients requiring inpatient transplant evaluation

BACKGROUND

Indications to refer patients with cirrhosis for liver transplant evaluation (LTE) include hepatic decompensation or a model for end stage liver disease (MELD-Na) score ≥ 15. Few studies have evaluated how delaying referral beyond these criteria affects patient outcomes.

AIM

To evaluate clinical characteristics of patients undergoing inpatient LTE and to assess the effects of delayed LTE on patient outcomes (death, transplantation).

METHODS

This is a single center retrospective cohort study assessing all patients undergoing inpatient LTE (n = 159) at a large quaternary care and liver transplant center between 10/23/2017-7/31/2021. Delayed referral was defined as having prior indication (decompensation, MELD-Na ≥ 15) for LTE without referral. Early referral was defined as referrals made within 3 mo of having an indication based on practice guidelines. Logistic regression and Cox Hazard Regression were used to evaluate the relationship between delayed referral and patient outcomes.

RESULTS

Many patients who require expedited inpatient LTE had delayed referrals. Misconceptions regarding transplant candidacy were a leading cause of delayed referral. Ultimately, delayed referrals negatively affected overall patient outcome and an independent predictor of both death and not receiving a transplant. Delayed referral was associated with a 2.5 hazard risk of death.

CONCLUSION

Beyond initial access to an liver transplant (LT) center, delaying LTE increases risk of death and reduces risk of LT in patients with chronic liver disease. There is substantial opportunity to increase the percentage of patients undergoing LTE when first clinically indicated. It is crucial for providers to remain informed about the latest guidelines on liver transplant candidacy and the transplant referral process.